Process for treating ricinoleic acid compounds



Patented May 11, 1943 PROCESS FOR TREATING RICIN OLEIOACID COMP OUNDS Gifford D. Davis, South Orange, N. J., and Bernard A. Dombrow, New York, N. Y., assignors to National Oil Products Company, Harrison, N. J a corporation of New Jersey No Drawing. Application November 22, 1940, Serial No. 366,704

11 Claims.

This invention relates to the treatment of ricinoleic acid compounds, more particularly to the conversion of castor oil or the fatty acids obtained therefrom into sebacic acid or omegahydroxydecanoic acid.

As is well known, sebacic acid has heretofore been prepared by fusion of castor oil with a strong alkali. This process is, however, unsatisfactory in many respects. In the first place, castor oil soap is formed in the preliminary stages of the reaction, which soap forms a relatively hard mass that is difficult to stir and prevents uniform heating of the reaction ingredients; as a result, considerable local overheating may take place, whereby charting and consequent loss of product result. Furthermore, a certain hazard is involved in this reaction because the hydrogen evolved may ignite at the elevated temperatures employed. Another important disadvantage is that the process may be carried out only as a batch operation requiring cumbersome and expensive equipment. The combination of these disadvantages has rendered the above process for the manufacture of sebacic acid from castor oil highly disadvantageous and there has been a great demand for processes which would provide a simpler and more economical method of accomplishing the desired results.

. In an attempt to satisfy this demand, it has been proposed to react castor oil or its fatty acids with a strong alkali in an aqueous medium under pressures sufiiciently high to prevent escape of the water vapor at the elevated temperatures employed. The disadvantage of this process, however, is that it requires the employment of equipment capable of withstanding the extremely high pressures generated by the water at the temperature of the reaction. As a result this process has not provided a completely satisfactory solution to the above demand.

It has also been proposed to manufacture sebacic acid or omega-hydroxydecanoic acid by slowly adding a ricinoleic acid compound, e. g. castor oil, to an aqueous solution of a strong alkali at elevated temperatures, permitting water and volatile reaction products to distill from the reaction mass, and then returning the water to thesystem to control the reaction temperature. The disadvantage of this process is that highly As a result of the disadvantages inherent in the above processes, there is still a demand in the art for a simple and inexpensive method for the manufacture of sebacic acid or omega-hydroxydecanoic acid from ricinoleic acid compounds, which demand has not, as yet, been completely satisfied.

The object of this invention is to provide a simple and economical process for the conversion of ricinoleic acid compounds into sebacic acid or strong alkali and an inert hydrocarbon oil haveflicient and rather complicated condensing apparatus must be employed in order to quickly retumthe water volatilized from the reaction mass to the vessel in which the reaction is being carried out.

ing a boiling point above about C. In accordance with our process, the ricinoleic acid compound reacts withthe strong alkali to form either sebacic acid and' a product comprising chiefiy-cctanol-2, or omega-hydroxydecanoic acid and a product comprising chiefly methylhexyl ketone, the particular products obtained depending upon the temperature'at which the reaction is carried out. Our process may be carried out at atmospheric pressures, thereby obviating the necessity of employing high pressure equipment; furthermore, since none of the volatile ingredients distilled off has to be returned to the reaction mixture, the operation of our process does not require the use of an elaborate and expensive condensing apparatus. We have found that the process of our invention furnishes the desired products in excellent yields and in extremely pure condition, and that it is highly effective and economical from an operating standpoint.

The ricinoleic acid compound employed in the process of our invention is preferably either castor oil or the ,fatty acids obtainable therefrom. However, it is to be understood that other esters of ricinoleic acid may be employed, as well as other ricinoleic acid derivatives capable of reacting with strong alkalis in the manner desired, e. g. ricinoleic amides. Furthermore, oils other than castor oil, e. g. grapeseed oil, which contain appreciable quantities of ricinoleic acid compounds may also be utilized to obtain the desired starting materials. Thus the term ricinoleic acid com- .pound is employed throughout the specification,

and claims to include substances of the type above described.

The medium in which the process of our invention is carried out may be any inert organic liquid having a relatively high boiling point; by inert. we mean that the liquid employed should not react with any ofthe-reaction ingredlents or reaction products at the temperature at which the process is carried out. We prefer to employ inert hydrocarbon oils having initial boiling points above about 180 C., preferably between about 240 C. and about 400 C. As examples of such oils there may be mentioned the various grades of mineral oil, preferably white mineral oils, high boiling kerosenes, diphenyl, naphthalene and alkylated naphthalenes, and other fractions obtained from either distillation of petroleum or coal tar, whose boiling points are above about 180 C. However. other inert organic liquids having-appropriate boiling points, such as halogenated aromatic hydrocarbons ofthe type of chlorinated naphthalenes, may also be used to advantage.

In carrying out the preferred embodiment of our invention a white mineral oil having a boiling range within the limits of 240 C. to 400 C. may be heated to a temperature between about 180 C. and about 300 0., and an aqueous solution of a strong alkali such as sodium or potassium hydroxide may then be added thereto, whereby a suspension of the strong alkali in the mineral oil is formed. The amount of alkali added to the oil may vary, but generally the mixture of oiland alkali thus produced should contain between about 1% and about 30% alkali. When the oil-alkali mixture has thus been prepared, the temperature of the mass may be adjusted, if necessary, to the point at which the reaction of the ricinoleic acid compound with the alkali is to be performed. If sebacic acid is desired, the temperature of the mineral oilalkali mixture during the reaction is preferably maintained between about 240 C. and about 340 0., whereby an alkali sebacate and octanol-2, the latter usually containing varying amounts .of methylhexyl ketone, are produced; on the other hand, if it is desired to produce chiefly omegahydroxydecanoic acid, the oil-alkali mixture is most advantageously maintained at a temperature between about 180 C. and about 220 C., whereby an alkali salt of omega-hydroxydecanoic acid and methylhexyl ketone, the latter usually containing some octanol-Z, are obtained.

is preferably carried out at atmospheric pressure, the octanol-2 or methylhexyl ketone easily distill from the reaction mass, along with any water that may be present, and are subsequently condensed. These products may be separated from the water and recovered in any suitable manner.

The residue remaining in the reaction vessel at the end of this process consists of an alkali salt of the acid produced by the reaction, together with most of.the mineral oil employed as the reaction medium; To recover the desired acid, the mass may first be extracted with water in order to separate the salts from the mineral oil. The aqueous solution thus obtained may then be partially acidified to a pH value of about 6 by the addition thereto of a mineral acid such as sulfuric or hydrochloric acid in order to cause any fatty acids and other fatty impurities which may be contained in the solu tion to separate therefrom; these fatty acids may be removed as desired. The solution thus obtained may then be further acidified to a pH value of anywhere from 1 to 4 in order to convert the salts remaining in the solution into the desired free acids, which acids thereupon When the temperature of the oil-alkali mixture has been suitably fixed, the ricinoleic acid compound to be reacted with the alkali may be gradually added to the oil-alkali mixture, the mass being strongly agitated throughout the reaction. .Preferably the ricinoleic acid compound contains water in an amount such that between about one and about three mols of water for every mol of ricinoleic acid compound is added to the oil-alkali mixture. The amount of ricinoleic acid compound introduced into the reaction mixture should be such as to react. substantially completely with the alkali and may vary with the particular compound used; for example, between about 1 and about 4 parts of castor fatty acids per part of anhydrous sodium hydroxide are suitable. The ricinoleic acid compound reacts with the alkali in such a manner that a salt of sebacic acid or omega-hydroxydecanoic acid is formed, the other products of the reaction being chiefly oetanol-2 or methylhexyl ketone, respectively.

Since the reaction crystallize from the aqueous solution; the crystallization may be accelerated by cooling. We have found that the products thus obtained are substantially pure white and crystallize from the aqueous solution in excellent yields.

While the above detailed description has dealt with the preferred embodiment of our invention, it is to be understood that this process may be varied somewhat without departing from the scope of the invention. For example, the aqueous solution of the strong alkali may be mixed with the inert reaction medium at ordinary temperatures and the mixture then heated to the desired temperature. Furthermore, a hot aqueous solution containing an alkali ricinoleate and a strong alkali may be gradually added to the hot inert reaction medium, whereby the ricinoleate decom poses into the desired products. The process may be made continuous by continuously adding the appropriate reactants to the inert reaction medium, continuously distilling the volatile ingredients from the reaction mass, continuously withdrawing the salts of the desired acids therefrom. and recirculating the reaction medium. In some cases it has been found desirable to pass steam through the final reaction product in order to remove the last traces of octanol-Z or ketone therefrom prior to the recovery of the free acids. If desired, pressures somewhat above atmospheric may be employed, but this is not preferred for reasons l'iereinabove'mentioned. Many other variations in the process described may also be made without departing from the essential features of this invention.

As will be evident from the above description, the-reaction involved in the process of our invention is heterogeneous, since none of the reaction ingredients is ordinarily miscible with the reaction medium; hence it is of the utmost importance that the reaction mass be thoroughly agitated during the course of the reaction. It is most surprising that such a heterogeneous reaction gives excellent yields of the desired products in a simple and economical manner, since as is well known, many heterogeneous reactions go to completion only with difliculty because of improper contact of the reacting ingredients; in the inrizant process, however, such difficulties do not 8 e.

The following examples are illustrative of our invention; amounts are given in parts by weight.

Example I 175 parts of a white mineral oil having a boiling range between about 300 0. and about 400 C. were heated to a temperature of about 250 0., and 55 parts of a 50% aqueous sodium hydroxide solution were gradually added to the hot mineral oil, the water being permitted to'distill from the hot oil. After all the alkali had been added, the temperature of the oil-alkali mixture was raised to about 270 C. and 100 parts of castor oil fatty acids mixed with aboutlO parts of water were gradually added to the mass with constant agitation over a period of about 50 minutes, the temperature being maintained between about 270 C. and about 280 C. During the course of the reaction, vapors were continuously evolved and these vapors were condensed. The con- Example II A mixture of mineral oil and alkali was prepared as described in Example I and 100 parts of castor oil fatty acids mixed with parts of water were then gradually added thereto with constant agitation, the temperature of the oilalkali mixture being maintained at about 180 C. The reaction mass was then worked up as described in Example 1, whereby a product comprising chiefly methylhexyl ketone was recovered from the condensate and omega-hydroxydecanoic acid was obtained from the residue.

It will be evident from the above description that the process of our invention provides a highly simplified procedure for the conversion of ricinoleic compounds into valuable constituents. Our process is obviously more simple and satisfactory than the fusion process heretofore employed; furthermore, it can be carried out at atmospheric pressure without the necessity of using special condensing equipment and hence possesses important advantages over other proposed processes. Because of the many advantages inherent in our process, it will undoubtedly be of great interest to those engaged in the manufacture of sebacic or omega-hydroxydecanoic acids.

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

- Having described our invention, what we claim as new and desire to secure by Letters Patent, is: 1. A process for the conversion of ricinoleic acid compounds, which comprises reacting a rici'noleic acid compound with a strong alkali at elevated temperatures in a medium constituted chiefly of an inert organic liquid having a relatively high boiling point said inert organic liquid being present in a quantity greater than that of the alkali.

2. A process for the conversion of ricinoleic acid compounds, which comprises reacting a ricinoleic acid compoundwith a strong alkali at elevated temperaturesin a medium constituted chiefly of an inert hydrocarbon oil having a boiling point above about 0., said inert hydrocarbon oil being present in a quantity greater than that of the alkali.

3. A process for the conversion oiflricinoleic acid compounds, which comprises reacting a ricinoleic acid compound containing a small amount of water with a strong alkali at atmospheric pressure and at a temperature between about 180 C. and about 340 C. in a medium constituted chiefly of an inert hydrocarbon oil having a boiling point above about 180 0., said inert hydrocarbon 011 being present in a quantity greater than that of the alkali collecting the distillate from the reaction mass, and recovering the acid produced by the reaction from the residue.

4. A process for the preparation of sebacic acid from ricinoleic acid compounds, which comprises reacting a ricinoleic acid compound with a strong alkali at a temperature above about 240 C. in a medium constituted chiefly of an inert hydrocarbon oil having a boiling point above about 180 0., said inert hydrocarbon oil being present in a quantity greater than that of the alkali.

5. A process for the preparation of sebacic acid from ricinoleic acid compounds, which comprises gradually adding a ricinoleic compound containing a relatively small amount of water to a strong alkali dispersed in a medium constituted chiefly of an inert hydrocarbon oil having a boiling range within the limitsv of about 240 C. to about 400 0., said inert hydrocarbon oil being present in a quantity greater than that of the alkali and being maintained at a temperature between about 240 C. and about 340 0. during the addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising octanol-2 from said distillate, and recovering sebacic acid from the residue.

6. A process for the preparation of sebacic acid from ricinoleic acid compounds, which comprises adding a solution of sodium hydroxide to an inert hydrocarbon oil heated to a temperature suificiently high to cause the water to distill from the solution, thereby forming a mixture containing a major portion of inert hydrocarbon oil and from about 1% to about 30% alkali, gradually adding castor fatty acids containing a relatively small amount of water to the oil-alkali mixture with strong agitation, said mixture being maintained at a temperature between about 240 C. and about 340 C. during the addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising octanol-2 from said distillate, extracting the residue with boiling water, partially acidifying the aqueous extract with a mineral acid, removing the oily layer which separates, further acidifying the aqueous extract until sebacic acid crystalsappear, and recovering the sebacic acid.

'I. A process for the preparation of omega hydroxy-decanoic acid from ricinoleic acid compounds, which comprises reacting a ricinoleic acid compound with a-strong alkali at a temperature above about 180 0. in a medium constituted chiefly of an inert hydrocarbon oil having a boiling point above about 180 C., said inert hydrocarbon oil being present in a quantity greater than that or the alkali.

8. A process for the preparation of omegahydroxy-decanoic acid from ricinoleic acid compounds, which comprises gradually adding a ricinoleic acid compound containing a relatively small amount of water to a strong alkali dispersed in a medium constituted chiefly of an inert hydrocarbon oil having a boiling range within the limits of about 240 C. to about 400 C., said inert hydrocarbon all being present in a quantity greater than that of the and being maintained at a temperature between about 180 C.

and about 220 C. during the addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising methylhexyl ketone from said distillate, and recovering omega:- hydroxydecanoic acid from the residue.

9. A process for the preparation of omegahydroxy-decanoic acid from ricinoleic acid compounds, which comprises adding a solution of sodium hydroxide to an inert hydrocarbon oil heated to a temperature sufficiently high to cause the water to distill from the solution, thereby forming a mixture containing a major portion of inert hydrocarbon oil and from about 1% to about 30% alkali, gradually adding castor fatty acids containing a relatively small amount of water to the oil-alkali mixture with strong agitation, said mixture being maintained at a temperature between about 180 C. and about 220 C. during the.

addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising methylhexyl ketone from said distillate, extracting the residue with boiling water, partially acidifying the aqueous extract with a mineral acid, re-

moving the oily layer which separates, further acidifying the aqueous extract until omega-hy droxydecanoic acid crystals appear, and recovering the omega-hydroxydecanoic acid.

10. A process for the preparation of sebacic acid from ricinoleic acid compounds, which comprises adding a solution of sodium hydroxide to a mineral oil having a boiling range within the limits of about 240 C. to about 400 6., said oil being heated to a temperature sufliciently high to cause thewater to distill from the solution,- thereby forming a mixture containing a major portion of inert hydrocarbon oil and from about 1% to about alkali, gradually adding castor fatty acids containing a relatively small amount of water tov the oil-alkali mixture with strong agitation', said mixture being maintained at a temperature between about 240 C. and about 340 C. during the addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising octanol-2 from the said distillate, ex tracting the residue with boiling water, partially acidifying the aqueous extract with a mineral acid, removing the oily layer which separates, further acidifying the aqueous extract until sebacic acid crystals appear, and recovering the sebacic acid.

11. A process for the preparation of omegahydroxy-decanoic acid from ricinoleic acid compounds, which comprises adding a solution of sodium hydroxide to a mineral oil having a boiling range within the limits of about 240 C. to about 400 0., said oil being heated to a temperature sufliciently high to cause the water to distill from the solution, thereby forming a mixture containing a major portion of inert hydrocarbon oil and from about 1%. to about 30% alkali, gradually adding castor fatty acids containing a relatively small amount of water to the oil-alkali mixture with strong agitation, said mixture being maintained at .a temperature between about 180 C. and about 220 C. during the addition of the ricinoleic acid compound thereto, collecting the distillate evolved from the reaction mass and recovering a product comprising methylhexyl ketone from the said distillate, extracting the residue with boiling water, partially acidifying the aqueous extract with a mineral acid, removing the oily layer which separates, further acidifying the aqueous extract until omega-hydroxydecanoic acid crystals appear, and recovering the omegahydroxydecanoic acid.

GIFFORD D. DAVIS.

BERNARD A. DOMBRow.

EEEfiF i CA TE O F EOfiRiif dN I Patent No. 2,518,762. I May 11, 194.5. I

iGIFFCRD D. DAVIS, 'ET AL.

Itis hereby certified'tl' at error appeare in the printed specification of the above numbered patent reqx iring correction as follows: Page}, aec

0nd column, line 51+, clair n's 5 for 'ricinoleic compound" I read --ricino1eic aoid compound"; and thatthe said Letters Pater 1t should be read with this oorrection' therein that the {same may conform to the record of the ease in the Patent Qfifice. I

Signed amt sealed tiiisjfggmfdg of June, I A. D. 1915.

. Henry Van Ar s daie, (Seal) Actin g Commissioner of Patents. 

